diff --git a/core-java-collections/src/main/java/com/baeldung/java/list/WaysToIterate.java b/core-java-collections/src/main/java/com/baeldung/java/list/WaysToIterate.java new file mode 100644 index 0000000000..3cce08eabb --- /dev/null +++ b/core-java-collections/src/main/java/com/baeldung/java/list/WaysToIterate.java @@ -0,0 +1,67 @@ +package com.baeldung.java.list; + +import java.util.Arrays; +import java.util.Iterator; +import java.util.List; +import java.util.ListIterator; + +/** + * Demonstrates the different ways to loop over + * the elements of a list. + */ +public class WaysToIterate { + + List countries = Arrays.asList("Germany", "Panama", "Australia"); + + /** + * Iterate over a list using a basic for loop + */ + public void iterateWithForLoop() { + for (int i = 0; i < countries.size(); i++) { + System.out.println(countries.get(i)); + } + } + + /** + * Iterate over a list using the enhanced for loop + */ + public void iterateWithEnhancedForLoop() { + for (String country : countries) { + System.out.println(country); + } + } + + /** + * Iterate over a list using an Iterator + */ + public void iterateWithIterator() { + Iterator countriesIterator = countries.iterator(); + while(countriesIterator.hasNext()) { + System.out.println(countriesIterator.next()); + } + } + + /** + * Iterate over a list using a ListIterator + */ + public void iterateWithListIterator() { + ListIterator listIterator = countries.listIterator(); + while(listIterator.hasNext()) { + System.out.println(listIterator.next()); + } + } + + /** + * Iterate over a list using the Iterable.forEach() method + */ + public void iterateWithForEach() { + countries.forEach(System.out::println); + } + + /** + * Iterate over a list using the Stream.forEach() method + */ + public void iterateWithStreamForEach() { + countries.stream().forEach((c) -> System.out.println(c)); + } +} \ No newline at end of file diff --git a/core-java-collections/src/test/java/com/baeldung/java/list/WaysToIterateUnitTest.java b/core-java-collections/src/test/java/com/baeldung/java/list/WaysToIterateUnitTest.java new file mode 100644 index 0000000000..973c60b233 --- /dev/null +++ b/core-java-collections/src/test/java/com/baeldung/java/list/WaysToIterateUnitTest.java @@ -0,0 +1,71 @@ +package com.baeldung.java.list; + +import static org.junit.Assert.assertEquals; + +import java.util.ArrayList; +import java.util.Arrays; +import java.util.Iterator; +import java.util.List; +import java.util.ListIterator; + +import org.junit.Test; + +public class WaysToIterateUnitTest { + + List globalCountries = new ArrayList(); + List europeanCountries = Arrays.asList("Germany", "Panama", "Australia"); + + @Test + public void whenIteratingUsingForLoop_thenReturnThreeAsSizeOfList() { + for (int i = 0; i < europeanCountries.size(); i++) { + globalCountries.add(europeanCountries.get(i)); + } + assertEquals(globalCountries.size(), 3); + globalCountries.clear(); + } + + @Test + public void whenIteratingUsingEnhancedForLoop_thenReturnThreeAsSizeOfList() { + for (String country : europeanCountries) { + globalCountries.add(country); + } + assertEquals(globalCountries.size(), 3); + globalCountries.clear(); + } + + @Test + public void whenIteratingUsingIterator_thenReturnThreeAsSizeOfList() { + Iterator countriesIterator = europeanCountries.iterator(); + while (countriesIterator.hasNext()) { + globalCountries.add(countriesIterator.next()); + } + + assertEquals(globalCountries.size(), 3); + globalCountries.clear(); + } + + @Test + public void whenIteratingUsingListIterator_thenReturnThreeAsSizeOfList() { + ListIterator countriesIterator = europeanCountries.listIterator(); + while (countriesIterator.hasNext()) { + globalCountries.add(countriesIterator.next()); + } + + assertEquals(globalCountries.size(), 3); + globalCountries.clear(); + } + + @Test + public void whenIteratingUsingForEach_thenReturnThreeAsSizeOfList() { + europeanCountries.forEach(country -> globalCountries.add(country)); + assertEquals(globalCountries.size(), 3); + globalCountries.clear(); + } + + @Test + public void whenIteratingUsingStreamForEach_thenReturnThreeAsSizeOfList() { + europeanCountries.stream().forEach((country) -> globalCountries.add(country)); + assertEquals(globalCountries.size(), 3); + globalCountries.clear(); + } +} \ No newline at end of file